This invention involves cutting and forming panels. More specifically, it involves cutting porous panels, including fibrous reinforced panels and forming them to arcuate shapes. It specifically involves a cutting device and a method of cutting arc shapes out of porous panels. It specifically involves the method of forming and bending flat panels into a curved shape.
In the building and construction field there are a large number of relatively porous panels used in a variety of applications. These panels include rigid and semi-rigid polymeric foam panels, generally with one or more paper, plastic or metal film surfaces adhered to a surface. Also included in this general grouping are particle boards which are low pressure laminates of cellulosic fibers bound together, generally for indoor usage. Of particular interest are low pressure fiberglass reinforced laminates generally known in the field as "duct board" supplied commercially by CertainTeed Corporation, Mansville Corporation and Owens-Corning Fiberglass Corporation. The duct board is formed of glass fiber mat bound with little or no pressure together with an adhesive resin material to form a rigid panel board with an aluminum foil sheet bonded to one surface. An example of this material ULTRA* DUCT FIBER GLASS BOARD supplied by CertainTeed Corp., P. O. Box 860, Valley Forge, Pa. 19482. This material is used to construct residential and commercial heating and air conditioning ducts. The aluminum foil is positioned on the outside of the constructed duct section and flax extensions of the foil are used to overlay and allow attachment of the panels of the duct board together using staples. The ducts usually range in size from about eight inches by eight inches to about ten inches by thirty inches. The individual panels of duct board are attached end to end generally using male and female ship lap joints with the aluminum foil, staples, and duct tape to form the duct which is held in position by metal straps and trapeze hangers. This type of construction has largely replaced the metal duct work of the past, particularly in residential buildings.
When the duct work constructed of duct board is required to turn a corner, either horizontally or vertically, a problem has arisen. Metal duct work was bent and formed to form curved corners to minimize pressure drop and interference with the air flow. The square corner sections constructed of duct board had unsatisfactory flow characteristics as the air banged against the end of the corner which was normal to the air flow thus causing a substantial pressure drop and reduction in air flow. The solution to this problem has been to insert a baffle plate at a forty-five degree angle across the corner inside the duct corner section. This baffle plate includes small air scoops which are curved to catch the air and throw it around the corner in the new direction. This baffle plate must be inserted and attached inside the duct board corner section after it has been constructed. Since the duct board duct section is only marginally structural in nature, expensive and time consuming attachments are necessary to insert and retain the turning-vane device. Further, the air flow is substantially disrupted and the system is only marginally effective in reducing the pressure drop as the air flow turns the corner.
No satisfactory system or device has been disclosed or made available to satisfy the above problems or to achieve the objects described hereinbelow.